This disclosure directs itself to a tone control for string instruments that permits selective filtering of one or more pickup sensors, active or passive, of the instrument. More in particular, the disclosure is directed to a tone control for string instruments that includes a pair of potentiometers each coupled in series relationship with a respective filter capacitor and mechanically coupled one to the other for concurrent mechanical travel of respective displaceable contacts thereof. Still further, the disclosure is directed to a system where responsive to selective positioning of the displaceable contacts of the pair of potentiometers, the signals input thereto are high pass filtered, low pass filtered or unfiltered. The disclosure is also directed to a tone control that operates with two pickup coils coupled in series to provide low pass filtering of one pickup coil and a high frequency boost for the other pickup coil.
Electric string instruments, such as electric guitars, electric bases, electric violins, etc., use one or more pickup sensors to convert the vibration of instrument's strings into electrical impulses. The most commonly used pickups uses the principle of direct electromagnetic induction. The signal generated by the pickup is of insufficient strength to directly drive an audio transducer, such as a loudspeaker, so it must be amplified prior to being input to the audio transducer.
Because of their natural inductive qualities, all magnetic pickups tend to pick up ambient electromagnetic interference (EMI) from electrical power wiring in the vicinity, such as the wiring in a building. The EMI from a 50 or 60 Hz power system can result in a noticeable “hum” in the amplified audio by from the audio transducer, particularly with poorly shielded single-coil pickups.
While most single coil pickups are wired in parallel with each other, it is also possible to wire them in series, producing a fuller and stronger sound. Using a multiple pole, multiple through switch, such as a double pole, double through switch (DPDT) or double pole three position switch, it is known in the art to switch the coil configuration between series and parallel, and may also provide or “coil cut” configuration (a single coil output). It is also known to use ganged potentiometers to provide series to parallel blending.
Networks formed by ganged or individual potentiometers with series coupled capacitors for “treble control” and parallel coupled capacitors for “bass control” have been used for many years. However, such controls do not give the musician the option for a natural unfiltered sound without the use of a switch to bypass the tone control network. It is an object of the invention disclosed herein to overcome that and other deficiencies in the prior art